Siphon valve



April 14, 1970 F. P. SLOAN 3,505,688

SIPHON VALVE Filed Feb. l2, 1968 5 Sheets-Sheet 1 11\ VISA/TOR FRAN KPHI LIP SLOAN F. P. SLOAN SIPHON VALVE April 14, 1970 Filed Feb. 12,1968 38 I, E l:

5 Sheets-Sheet 2 l VENTOR FRANK PHI LIP SLOAN April 14, 1970 F. P. SLOAN3,505,688

SIPHON VALVE Filed Feb. 12, 1968 5 Sheets-Sheet 5 INVEN TOR. FRANK PHILIP SLOAN April 14, 1970 F. P. SLOAN 3,505,688

SIPHON VALVE Filed Feb. 12, 1968 5 SheetsSheet 5 T0 TANK DHAY T/MER (/0SEC.)

70 PIP/MARY All? OPf/V/NG mvzavroza. FRANK PHILIP SLOAN United StatesPatent Ofi ice 3,505,688 Patented Apr. 14, 1970 3,505,688 SIPHON VALVEFrank Philip Sloan, 19 Lascelles Blvd., Toronto 7, Ontario, CanadaContinuation-impart of abandoned application Ser. No. 499,715, Oct. 21,1965. This application Feb. 12, 1968, Ser. No. 704,593

Int. Cl. E03d N08 US. Cl. 4-42 29 Claims ABSTRACT OF THE DISCLOSURE Asiphon valve primarily for toilet tanks, having primary and secondarysiphons joined at an intermediate bend to form an M-shaped structure. Arelatively large tertiary siphon inside the secondary siphon extendsfrom just above the intermediate bend to the secondary siphon outlet.Water enters the primary siphon and discharges through the secondary andtertiary siphons, flow commencing upon release of air through an airopening in the top of the primary siphon.

From the air opening, a duct leads to a secondary air inlet located in asecondary reservoir between the siphons. The secondary reservoir has asmall drain hole so that water drains therefrom, to expose the secondaryair inlet, at a rate slower than the emptying of the tank through thesiphon valve.

This application is a continuation-in-part of my cpending applicationSer. No. 499,715 filed Oct. 21, 1965, now abandoned.

This invention relates to a siphon valve for a liquid reservoir. Itparticularly relates to a self-correcting siphon valve suitable as aflush device for a toilet tank or the like.

Various attempts have been made in the past to provide siphon valves inwhich the siphon flow is interrupted in one way or another by an airbubble. These devices have geenrally been unsuccessful, because theyhave had to cope with widely varying operating conditions and they havegenerally been unable to meet such conditions. A particularly commonproblem in prior art devices is that once a malfunction or abnormalevent occurs, they have been unable to correct themselves to restorenormal operation.

Therefore, it is an object of the present invention in one of itsaspects to provide a self correcting siphon valve that will restoreitself to normal operation in the event of incorrect operation. In thedevice provided by the invention, there are no moving parts except foran air release button, so the resultant valve has a very long life andrequires little or no maintenance.

In a typical embodiment of the invention, a double siphon is provided,formed from an inverted U-shaped primary siphon, connected at anintermediate bend to an inverted U-shaped secondary siphon, the wholehaving the appearance generally of the leter M. A tertiary siphon islocated in the secondary siphon to siphon some water from theintermediate bend after a flush but to leave enough water to provide anair trap in the intermediate bend, and to perform other functionsdescribed in more detail presently. A primary air opening is provided inthe primary siphon to initiate flushing by releasing trapped air, and asecondary air inlet and a timer are provided to terminate a flush and toenable correcting action, as will be pear from the followingdescription, taken with the accompanying drawings, in which:

FIG. 1 is a perspective view of a first embodiment of the invention,indicated as located in a toilet tank FIG. 2 is a vertical section ofthe device of FIG. 1;

FIG. 3 is an underside view of the device of FIG. 1;

FIG. 4 is an end elevation of the device of FIG. 1;

FIG. 5 is a section on the line 55 of FIG. 2;

FIG. 6 is an enlarged view of an actuating control or push button,partly cut away, for use with the device of FIG. 1;

FIGS. 7 to 12 illustrate different stages of operation of the device ofFIG. 1;

FIG. 13 is a side view, partly in section, of a modification of thedevice of FIG. 1 as installed in a toilet tank;

FIG. 14 is a perspective view of a portion of the device of FIG. 13;

FIG. 15 is a section along line 1515 of FIG. 13, and

FIGS. 16 and 17 show a further modification of the invention.

Reference is first made to FIG. 1, which shows a typical self-correctingsiphon valve 10 according to the present invention. The valve 10 isshown installed in a toilet tank indicated in chain lines at 12, thetoilet tank being provided with a conventional water inlet pipe 14,inlet float valve 16, float arm 18, and float 20 to turn the inlet valveon and off as the float falls and rises respectively.

The siphon valve 11 is shaped generally in the form of the letter M andincludes three siphons (FIG. 2), namely a primary siphon 22, a secondarysiphon 24, and a tertiary siphon 26 formed within the secondary siphon24. The primary siphon includes an inlet leg 28 having an inlet 30 inits lower end, an outlet leg 32 spaced from the inlet leg 28, and anupper bend 34 connecting the inlet and outlet legs.

The secondary siphon 24 is generally similar in form to the primarysiphon, having an inlet leg 36, an outlet leg 38 spaced slightly fromthe inlet leg 36, and an upper bend 40 connecting its inlet and outletlegs. The outlet leg 32 of the primary siphon is connected to the inletleg 36 of the secondary siphon by an intermediate bend 42.

The tertiary siphon 26 is defined by a member 44 spaced from anextending across and along the inner wall of the secondary siphon. Asmay be seen, the tertiary siphon includes an inlet leg 46 having aninlet 48 located just above the top of the intermediate bend 42, anoutlet leg 50 having an outlet 51 level with the outlet of the secondarysiphon, and an upper bend 52 joining its inlet and outlet legs.

The cross-sectional shapes of the primary, secondary and tertiarysiphons are generally rectangular, as shown in FIG. 5. However, theoutlet legs 38, 50 of the secondary and tertiary siphons are rounded attheir bottoms, as shown at 54, so they will fit into the standardfitting structure 56 (FIG. 1) usually provided in conventional toilettanks. The outlet legs 38, 50 of the secondary and tertiary siphonsextend well below the inlet 30 of the primary siphon, to provide suctionso that the device will operate as a siphon.

In the device shown, the cross-sectional area of the tertiary siphon,indicated by area A1 in FIGS. 3 and 5, is about one-quarter of thecross-sectional area A2 of the secondary siphon, for a reason to beexplained shortly.

In order to flush the unit, a primary air opening 58 is provided in theupper bend of the primary siphon, inlet 58 being defined by a fitting 60typically molded with the flush device 10. From the fitting 60, an airconduit 62 (FIG. 1) leads to an air release push-button 64.

In addition, a secondary air opening or inlet 66 is provided, inlet 66being defined by an opening in the bottom of a conduit 68 connected tothe fitting 60, so that the primary and secondary air openings 58 and 66are connected.

Finally, the flush device includes a secondary reservoir 70 located inthe space between the primary siphon outlet leg 32 and the secondarysiphon inlet leg 36. The reservoir 70 is termed a secondary reservoir todistinguish it from the primary or main reservoir defined by the toilettank 12. The bottom of the secondary reservoir is closed by the topsurface of the intermediate bend 42 and its sides are closed by a pairof cover plates 72 extending between the primary and secondary siphons.As may be seen from FIG. 2, the secondary air inlet 56 is locatedapproximately half way up the height of the secondary reservoir 70, i.e.it is located at a height 11/2 above the top of the intermediate bend42, when It is the height from the top of the intermediate bend to aboutthe top of the upper bends 34, 40.

One of the cover plates 72 of the secondary reservoir contains arelatively small drain aperture 74 therein, to permit water to drainfrom or enter the secondary reservoir at a timed rate. Aperture 74 maybe defined by a nipple insertable in the cover plate 72, so that theflow or drain rate through aperture 74 is adjustable by selecting thehole size for the nipple.

The operation of the device as so far described is as follows, referencebeing made to FIGS. 7 to 12, which illustrates operationdiagrammatically.

Assume that the device is located in the tank 12, and that the waterlevel 76 in the tank has reached height H (this being determined by thefloat valve 16). Assume that the float is set so that the head of waterover the device is slightly less than h/Z, where h is the height fromthe top of the intermediate bend 42 to the top of the upper bends 34,40. Assume further that the device has just completed a flush and refillcycle and has now reached equilibrium. The situation is then as follows(see FIG. 7).

Water 78 is present in the inlet leg 28 of the primary siphon, up to alevel just at the dam height of the upper bend 34. Compressed air 80 islocated in the upper bend 34 and in the outlet leg 32 of the primarysiphon, down to the intermediate bend 42. A Water trap 82 is present inthe intermediate bend and this water extends up the inlet leg 36 of thesecondary siphon and up the inlet leg 46 of the tertiary siphon, to aposition slightly below the upper bend 52 of the tertiary siphon. Air atatmospheric pressure is present in the remainder of the tertiary andsecondary siphons.

FLUSHING When a user wishes to flush the toilet, he pushes the airrelease button 64, permitting release of the compressed air 78. (Thebutton 64 should typically be held for at least one-half to one secondto release enough air to start a flush and may be held for up to aboutfour seconds without interferring with the flush.) The water head abovethe device forces water in the tank 12 into the primary siphon inlet 30,rapidly forcing out the air 78 and flushing begins. As water travelsthrough the primary, secondary and tertiary siphons, the water level inthe tank 12 rapidly drops.

As the water level 76 in the tank 12 drops, the Water level 84 in thesecondary reservoir 70 also drops, but it lags behind the water level inthe tank (FIG. 8). This lagging is caused by the relatively slowdraining of the secondary reservoir through drain aperture 74. Thesecondary reservoir is also drained slightly by suction draining throughthe secondary air inlet 66 into the primary siphon, after the tank waterlevel 76 has dropped well below the bottom of the upper bend 34.

As shown in FIG. 9, when the level 76 in the tank has dropped nearly tothe level of the inlet 30, the water level 84 in the secondary reservoirdrops below the secondary air inlet 66, exposing this inlet toatmospheric air. Since the tank water level 76 is below the upper bend34, the pressure in the upper bend 34 is below atmospheric pressure. Airis therefore sucked into the secondary air inlet, once it is exposed (asindicated by arrow B), and

4 a bubble of air 86 forms to interrupt the water flow and break thesiphon.

It is found that breaking the siphon in this manner eliminates theextreme turbulence (and also noise) that would be created if the primarysiphon inlet 30 were simply allowed to suck air to break the siphon.

With secondary air inlet 66 open to the air, the water level in theinlet leg 28 of the primary siphon falls back to the water level 76 inthe tank. The tertiary siphon 26, which is still primed, continues todraw water out of the outlet leg 32 of the primary siphon, theintermediate bend 42, and the inlet leg 36 of the secondary siphon,until the water level in the intermediate bend 42 drops to the level ofthe tertiary siphon. This action of the tertiary siphon takes only oneor two seconds. This situation is now as shown in FIG. 10.

TANK REFILL During the flush, the Water inlet valve 16 continues todeliver water into the tank 12, but of course at a much slower rate thanthe rate at which Water is being evacuated. Once the flush terminates,however, the water level in the tank begins to rise.

'As' the level in the tank rises and passes above drain aperture 74,water begins to enter secondary reservoir 70. The water level in thesecondary reservoir may lag slightly behind that in the tank 12, but anysuch lagging is far less pronounced than during the flush (since therate of water inflow during tank filling is less than the rate of wateroutflow during a flush).

As shown in FIG. 11, as the level 76 in the tank approaches the bottomof the upper bend 34, the water level 84 in the secondary reservoirpasses above the secondary air inlet 66 to close it off. The air trappedin the primary siphon then begins to compress as the water rises in thetank. As the water continues to rise in inlet leg 28, the air compressedbetween the water trap in the intermediate bend 42 and the water ininlet leg 28 drives the level in outlet leg 32 downwardly to the top ofintermediate bend 42.

As the water in the inlet leg 28 rises further, it spills over the upperbend 34 and drops to the intermediate bend 42. Because of the compressedair in outleg leg 32, water cannot rise in this leg. Therefore, thewater spilling over the upper bend 34 acts to increase the level in theinlet legs 36, 46 of the secondary and tertiary siphons, i.e. the waterlevel in these legs rises. Eventually, the level in the tank reaches aheight at which the float shuts off the Water inlet valve, at which timethe situation is restored to that shown in FIG. 7.

FLOAT OR INLET VALVE MALFUNCTION If the float sticks and fails to riseto shut off the inlet valve, then the water level in the tank 12continues to rise. This causes the water level in the inlet legs 36, 46of the tertiary and secondary siphons to rise, and the tertiary siphonbecomes primed and begins to draw water. The tertiary siphon thusperforms the function of an overflow pipe.

As previously mentioned, the tertiary siphon 26 has a cross-sectionalarea about one-quarter that of the secondary siphon 24. This is aboutthe same size as the overflow pipe of a conventional North Americantoilet (a conventional overflow pipe is about one-quarter of the outletarea in such conventional toilets). This size is suflicient to handle agreater flow than that into the tank 12 through the inlet valve 16.

The tertiary siphon therefore drains the tank 12 at a rate faster thanthat at which the tank is being filled, and the water level in the tankfalls. The level in the tank is closely followed by the level in thesecondary reservoir 70, because the draining of the tank by the tertiarysiphon is relatively slow (as compared with a flush). The primary siphonperforms a siphoning action at this time (although it has a large bubbleof air therein), sucking water into the inlet 30 to replace waterremoved by the tertiary si' phon 26.

When the water levels in the tank and secondary reservoir fall below thesecondary air inlet 66, the secondary air inlet is exposed toatmospheric air, breaking the primary siphon. The tertiary siphoncontinues to draw water from the intermediate bend 42 to leave a watertrap therein, and the tank 12 begins to refill, until the tank levelagain becomes high enough to prime the tertiary siphon. The resultantcycling of about half the contents of the tank is a distinctivecondition indicative of a faulty float valve and is easily detectable.In addition, the rise and fall of water in the tank will sometimesunstick the float valve.

INITIAL INSERTION OF THE DEVICE When the flush device is initiallyinserted in the tank 12 and the water is turned on, there will be nowater trap in the intermediate bend 42. Therefore, when the water in thesecondary reservoir 70 rises to a level at which it closes off thesecondary air inlet 66, the air in the outlet leg 32 of the primarysiphon will not compress until enough water has spilled over the upperbend 34 to establish a water trap in the intermediate bend.

As water spills into the intermediate bend 42, the intermediate bendfills to its top and, due to turbulence, usually fills to the top of thearrow 90 (FIG. 12). With the Water trap now established, air compressesin the outlet leg 32 of the primary siphon (due to the head 76 in thetank), but there is no surplus compressed air to drive the water levelin the bottom of the outlet leg 32 down to the top of the intermediatebend 42.

The extra height of water 94} in the outlet leg 32 of the primary siphoncauses a corresponding increase in height 92 in the levels in the inletlegs 36, 46 of the secondary and tertiary siphons. This usually willprime the tertiary siphon, causing it to draw and lower the level in thetank to a level at which the secondary air inlet is exposed to break theprimary siphon. The tertiary siphon 26 then siphons the correct amountof water from the intermediate bend 42 and the tank refills aspreviously described.

Thus, when the unit is initially installed and the water turned on, aninitial correcting action may occur.

CORRECTING ACTION Occasion for correcting action by the device occurs,as mentioned, when the float valve malfunctions, and may also occur, asmentioned, when the device is initially installed. A similar need forcorrecting action arises if the air push button 64 is pushed briefly(e.g. for less than one-half second) to release some air in the upperbend 34 of the primary siphon but not long enough to start a flush. Whenonly some of the air from the upper bend 34 is released and replaced bywater, the water level in the outlet leg 32 of the primary siphon rises,and the water in the inlet legs 36, 46 of the tertiary and secondarysiphons also rises and spills over the tertiary siphon upper bend 52.The tertiary siphon then draws Water and lowers the tank level until thesecondary air inlet 66 is exposed, following which the tank refills aspreviously described.

The need for correcting action also occurs if the air inlet button 64 ispushed briefly while the tank is refilling and air is being compressedin the upper bend. 34 and outlet leg 32 of the primary siphon. If someof this air is allowed to escape, then the water level in the outlet leg32 of the primary siphon rises, causing the water level in the inlet leg46 of the tertiary siphon to rise too high and spill over the upper bend52. The tertiary siphon 26 then draws to lower the tank level, andcorrecting action continues as previously described.

flush, if for example an obstruction should occur in the toilet bowl.The interruption is achieved by actuating the air button 64 to permitair to enter the primary siphon, destroying the siphoning action. It maybe noted that flow through the primary siphon will only be interruptedin this manner after the water level in the tank has dropped below thebottom of the upper bend 34. When the tank water level is above thisheight, the net head of Water continues to push water through thesiphons whether or not the primary air inlet 58 is exposed to theatmosphere.

From the foregoing explanation, it will be apparent that the tertiarysiphon 26 performs several functions. Firstly, it acts as an overflowpipe in case the tank water level becomes too high, thus eliminating theneed for a conventional overflow pipe. For this reason, the tertiarysiphon is sized, as discussed, so that it will remove water faster thanwater can be delivered into the tank 12 by the inlet valve 16. Forstandard North American toilets, this size is about one-quarter of thecross-sectional area of the secondary siphon, but this particular sizerelation can vary depending on the inlet valve and water pressureapplied thereto, and On the size of the secondary siphon (which canvary, depending on the dumping rate desired).

Secondly, the tertiary siphon, by virtue of its size, acts to lower thewater level in the tank 12 during correcting action (rather than merelypreventing the tank from overflowing). This action brings the tank waterlevel down to a height at which the secondary air inlet 66 is exposed,thus terminating the tank emptying and permitting the tank to refill(after which all flow ceases until the push button is actuated, unlessthe float valve is malfunctioning).

Thirdly, the tertiary siphon acts to siphon water from the intermediatebend 42 after the primary siphon has been broken (by exposure ofsecondary air inlet 66). The tertiary siphon removes enough Water toleave only a water trap at the bottom of the intermediate bend 42. Asdiscussed, if all the water in the intermediate bend were siphoned outafter each flush, then less air would be compressed in the outlet leg 32of the primary siphon during tank refilling, and the water levels wouldapproach those shown in FIG. 12, resulting in constant cycling orrunning. The cycling could be eliminated by reducing the water headabove the device, but in most applications, it is desirable to have ahigher head of water above the device, to obtain a better flush.

The extent to which the tertiary siphon draws the intermediate bend 42after a flush is variable. Sometimes the tertiary siphon leaves evenmore water in the intermediate bend 42 than shown in FIG. 10 (by reasonof air entering the tertiary siphon inlet, due to turbulence, andbreaking the tertiary siphon), and sometimes it leaves less (because ofwater momentum tending to empty the intermediate bend). However, it isdesirable to have the water level in the primary siphon outlet leg 32driven right down to the top of the intermediate bend 42 (as shown inFIG. 7) after the tank has refilled, so that the tank can be refilled tothe recommended level without the tertiary siphon overflowing.

For this reason, the secondary air inlet 66 and the timing meansconstituted by reservoir 70 and aperture 74, are arranged so that aircompression normally starts before the inlet leg 28 is full (asexplained in connection with FIG. 11). The compressed air then drivesthe primary siphon outlet leg water level down to the correct level. Thearrangement is such that usually there is more air compressed than isrequired for this task. The surplus air simply bubbles around theintermediate bend and provides an audible indication that the device isfunctioning properly.

It will be noted that the cross-sectional area of the inlet leg 28 ofthe primary siphon decreases from its inlet 30 to the commencement ofthe upper bend. This produces a smoother water flow into the device, andalso, it serves to compress more air in the upper bend 34 and outlet leg32 of the primary siphon once air compression starts (i.e. when thesecondary air inlet is covered with Water). The additional trapped airhelps drive the Water level in the primary siphon outlet leg 32 down tothe level of the top of the intermediate bend 42.

The location of the primary air inlet 58, at an angle of about 45degrees downstream of the midpoint of the upper bend 34, is important,since this is the only location at which all or most of the compressedair trapped in the primary siphon will be expelled, once flushing isinitiated. The exact optimum position of primary air inlet 58 willdepend to some extent on the velocity of flushing.

The secondary air inlet 66 serves several functions. Firstly, it breaksthe primary siphon before the tank water level drops to the inlet 30,thus preventing the noise and turbulence that would occur if thesiphoning action were broken by sucking air at the inlet 30. Thisfunction could of course be achieved equally well by having thesecondary air inlet outside the secondary reservoir 70, just above theinlet 30.

Secondly, the secondary air inlet, once exposed, feeds air into thedevice to allow the tertiary siphon 26 to extract all but the requiredamount of water from the intermediate bend 42. Again, the secondary airinlet could be located in the tank 12 just above the inlet 30 and itwould still perform this function.

Further, the secondary air inlet 66, together with the secondaryreservoir 70, enables the self correcting action of the unit. It isfound that if the secondary air inlet is located just above the primarysiphon inlet 30, then the tank water level will have to fall to a lowlevel during a correcting action before exposing the secondary air inletand initiating tank refilling. When the tank water level is this low, itis found that the tertiary siphon 26 will not function, becauseatmospheric air travels up the outlet leg 38 of the secondary siphon,down the inlet leg 36 of the secondary siphon, and into the inlet 48 ofthe tertiary siphon to break its siphoning action. This does not occurafter a flush when the tertiary siphon is draining the water from theintermediate bend 42 except that needed to supply a water trap,apparently because this adjusting action takes only a brief intervalafter the flush is completed and the secondary siphon outlet is exposedto atmosphere. However, air entry into the tertiary siphon inlet 48 doesoccur during correcting action by the tertiary siphon without a flush,if the tank water level is too low.

Such a failure of the tertiary siphon to act results in too much waterbeing left in the intermediate bend 42 when the tank 12 begins torefill. Therefore, when the tank fills up again, the water in thetertiary siphon 26 will spill over the upper bend 52, and continualrunning or cycling will occur. This is a condition commonly found inprior art siphon flushing devices; they are unable to correctthemselves.

The secondary reservoir 70, with its timing drain 74, solves thisproblem by breaking the primary siphon during a correcting action (i.e.when the tertiary siphon 26 is primarily responsible for tank drain)when the tank water level is still quite high. However, during a flush,when the tank'water level drops very rapidly, the secondary air inlet 66is not exposed until the tank has almost emptied, as described.

As shown in FIG. 2, the secondary air inlet 66 is located at a height h/2 above the top of the intermediate bend. The secondary air inlet shouldnot be located much below this level, since if the tank water levelfalls much below this level, air will enter the tertiary siphon inlet 48during correcting action and will prevent the tertiary siphon fromoperating. Conversely, the secondary air inlet 66 should not be muchabove the level shown, or it will be exposed too soon during a flushunless the drain hole 74 is made very small, and the smaller the drainaperture 74 is made, the greater is the likelihood of its clogging.

In order to feed air into the inlet fast enough to break the primarysiphon quickly and quietly, and to permit the tertiary syphon to operateefllciently, the secondary air inlet 66 and conduit 68 should be of areasonable size, e.g. equivalent to a A inch diameter tube. However, theinlet 66 and conduit 68 should not be too large, or they will suck watertoo rapidly from the secondary reservoir 70 during the latter stages ofa flush. Such draining would make it difficult to achieve the requiredtime delay in emptying the secondary reservoir, unless the drainaperture 74 in the secondary reservoir is made unduly small.

The drain aperture 74 in the secondary reservoir 70 must be sufficientlylarge that water will enter and rise in the secondary reservoir at areasonably rapid rate during tank refilling. If the water in thesecondary reservoir rises too slowly, it will take too long not only tocover secondary air inlet 66, but to cover this inlet to a depthsufficient to prevent air from being blown out inlet 66 as the tankrefills. This will result in air compression in the primary siphonstarting too late, and there may not be enough air to drive the waterlevel in the primary siphon outlet leg 32 down to the top of theintermediate bend 42.

It will be noted that during a correcting cycle, only half the tank isemptied and then refilled. This wastes less Water than if the entiretank were emptied, and correction is faster. A typical correcting cycle,including the time required for tank refill, will usually take about 40seconds with a typical siphon valve made according to the invention,i.e. it takes about the same time as that needed for a flush and tankrefilling.

The location shown for the secondary reservoir is convenient, since thisreservoir occupies no excess space (a factor to be considered in smallvolume toilet tank). The location shown has the further advantage thatthe reservoir is shaped somewhat in the form of a V as viewed from theside, i.e. its cross-section decreases toward its bottom. This has theadvantage that as the tank 12 drains, the water in the secondaryreservoir falls slowly at first, and then more rapidly as it passessecondary air inlet 66. This ensures a cleaner and more reproduciblebreak of the primary siphon. At the same time, the wide top of thesecondary reservoir enables it to hold more water, so that the drainaperture 74 need not be made unduly small.

However, it will be noted that the secondary reservoir could be locatedelsewhere than between the primary and secondary siphons. For example,it could be formed as a small cup, e.g. of polyethylene, of any desiredcross-section and could be hung near the push button 64. In this event,the conduit forming a secondary air inlet in the secondary reservoirwould lead to the conduit 62, i.e. conduit 62 would in effect be forked,one fork leading to the push button, and the other to the secondary airinlet.

The device shown is particularly suitable for molding from plastic. Asshown in FIGS. 3 to 5, it may be cast in two main half portions 100, 102to provide cementable seam flanges 104, 106 exterior of the flowpassages, with cementable overlapping walls 108, 110 which form themember 44 defining the tertiary siphon. After the two main halves arecemented (or otherwise fastened) together, the secondary reservoir sideplates 72 may be cemented to the structure. Usually both plates 72 willbe made from the same mold and will therefore each have a drain aperture74.

The M configuration shown for the siphons facilitates air testing of thedevice to see if there are leaks in the siphons. It is not of courseessential that this geometry be preserved, so long as primary andsecondary siphons in flow series are provided with a tertiary siphonassociated with the secondary siphon, but the geometry shown ispreferred. The width W of the unit is selected so that it will fit intoa standard size toilet tank.

The rectangular cross-section shown for the secondary and tertiarysiphons is advantageous for the following reasons. It is desirable tohave the tertiary siphon upper bend 52 as high as possible, so that ahigher head of water in the tank 12 can be achieved before the tertiarysiphon begins to overflow. Forming the tertiary siphon as a rectangularslit, as shown, decreases its dimension in the direction of arrow d(FIG. so that the height of the bottom of its upper bend 52 can beincreased.

Conversely, it is desirable to have the top of the secondary siphonupper bend 40 as low as possible below the water level in the tank, sothat the water head will drive the air from upper bend 40 during aflush. This is similarly achieved by stretching the secondary siphonlaterally into a rectangle. The lateral extent of the unit is governedby the dimensions of the tank 12 and the practicabilities of molding.

The air push button 64 may be of any desired construction. A typicalconstruction is shown in FIG. 6, in which the member 64 includes a valvemember 110 urged against a sealing O-ring 112 by a spring 114. Thespring 114 is located in a chamber 116 communicating with air conduit72. The valve member is pushed by a push rod 118 connected thereto, rod118 having a relieved portion defining part of a chamber 120. Chamber120 includes apertures 122 open to the air in its outer wall, so thatwhen push rod 116 is depressed, air may escape from chamber 116 tochamber 120 and through holes 122 to atmosphere.

Reference is next made to FIGS. 13 to 15, which illustrate amodification of the invention. The modification is similar in generalconfiguration to the siphon valve of FIGS. 1 to 12, so that only theadded features will be described. In FIGS. 13 to 15, primed referencenumerals indicate elements corresponding to those of FIGS. 1 to 12.

The first main feature of the siphon valve 10 of FIGS. 13 to is that itcontains an anti-siphon bowl refill tube and water level indicatorassembly generally indicated at 124. The assembly 124 comprises anupright tube 126 extending upwardly from an opening 127 in the uppersurface of the upper bend 40 of the secondary siphon, at a location justdownstream of the midpoint of the upper bend. The tube 126 is of fairlysubstantial internal diameter (e.g. one-half inch) and typically extendsseveral inches above the upper surface of the upper bend 40'. The tube126 terminates in a flat upper surface 128 having a smaller diametershort tube 130 projecting therefrom. A bowl refill conduit 132 extendsfrom the tube 130 to the inlet valve 16. The inlet valve 16' alsoincludes a tank refill conduit 134, to refill the tank 12'. A generallyelliptical water level indicator plate 136 is mounted on the tube 126near the top of the tube, to indicate the optimum water level 138.

The assembly just described operates as follows. After a flush, whilethe toilet tank 12' is refilling, the toilet bowl (not shown) must berefilled. The refilling is achieved by bowl refill conduit 132, whichfeeds water into the bowl refill tube 126 so long as the inlet valve 16is actuated (i.e. so long as the float is below the level needed to shutoff the inlet valve). The stream of water falling through the tube 126enters the outlet leg 38' of the secondary siphon and travels into thetoilet bowl. At the same time, inlet valve 16' refills the tank 12'through tank refill aperture 134.

Since the opening 127 is below the water level 138, there will be atendency for water in the tank to be siphoned into the tank refillconduit 134 and through the conduit 132 and tube 126 into the outlet leg38 when the tank is filled to level 138. Such a drain into the bowlwould cause the float to drop, actuating the inlet valve 16' and causingthe toilet to run continually. This problem can be avoided by providingan inlet valve 16 of the type that disconnects tank refill conduit 134from bowl refill conduit 132 when the inlet valve 16' is shut off, butsuch a solution requires a more costly inlet valve.

The assembly 124 solves the problem by providing a relatively largediameter tube 126 to a level above the normal water level 138, and asmaller diameter tube thereabove. Because of the difference in diametersbetween tubes 126, 130, air rises in tube 126 after a flush and killsany siphoning action in bowl refill conduit 132. Water therefore flowsfrom inlet valve 16' through conduit 132 so long as the inlet valve isactuated, but no water will siphon through. conduit 132 after the valveis shut off.

The location shown for the inlet tube 126 and aperture 127 serves afurther function. During a flush, water from the inlet valve is fedthrough conduit 132 and tube 126 and joins the water passing through theupper bend 40 of the secondary siphon. The water fed through tube 126 isunder considerable pressure and therefore assists the flushing action byassisting in the removal of any air trapped in the upper bend 40' of thesecondary siphon. So that the jet of water through tube 126 will assistthe flushing action, edge 140 of aperture 127 is rounded, and edge 142of aperture 127 is sharply angled. This causes water flowing throughaperture 127 to tend to hug the downstream side of the upper surface ofthe upper bend 40', so that it will assist rather than block the flush.

The size of the aperture 127 will depend on the water pressure availableat the inlet valve, but it must be large enough so that air will risethrough it to prevent siphoning from the bowl refill conduit 132, andyet should be small enough to provide a jet of water when the inletvalve 16 is actuated (to assist a flush).

It may be noted that the unit shown in FIG. 2 includes an aperturefitting 144 which is normally closed but which may be opened toaccommodate a bowl refill conduit similar to conduit 132. However, whena bowl refill conduit is coupled to fitting 144, the inlet valve 16should be of a type which closes off the tank refill conduit from thebowl refill conduit when the inlet valve is shut off, to preventdraining or siphoning of water from the tank into the secondary siphonoutlet leg 38.

The water level indicator 136 is provided so that persons using orinstalling the syphon valve device 10' may easily see the best operatinglevel. The elliptical shape of the indicator plate is so that it willnot interfere with the rise and fall of the float arm 18'.

The indicator 136 is thus set at the optimum water level for the deviceand indicates the proper setting for the float 20 and inlet valve 16.This is particularly useful when the device is used to replace theconventional flushing mechanism of a toilet being repaired, in whichcase the optimum water level for the device may be different than thewater level formerly used in the toilet tank.

The distance between the top of indicator 138 and the flat top 128 oftube 126 constitutes a safety margin. Once the water level reaches thetop 138, the tertiary siphon 126' begins to overflow (assuming that thedevice is functioning normally with sufficient air trapped in theprimary siphon), and if the water level should somehow reach the top ofshort tube 130, the device will go into a full flush (because the rateof flow will be fast enough to entrain and remove virtually all air inthe upper bends 34', 40).

The top 128 of the refill tube 126 therefore acts as an overflow levelindicator, so that a user may easily see the level at which the tertiarysiphon will overflow. In conventional toilets the overflow level isreadily visible in the form of the overflow pipe, but no overflow pipeis needed with the present invention, since the tertiary siphon conductsnormal overflow.

Since the water level can therefore never rise above the top of tube130, the hole for the air release push button 64 can safely be locatedjust above this level.

The second feature of interest in the device 10 is that the inlet 48' ofthe tertiary siphon is stepped slightly away from the smooth curve ofthe lower surface of the intermediate bend 42, as shown at 146. The step146 is into the inner wall of the secondary siphon 24'. This step isprovided because with the tertiary siphon inlet 48 located as shown inFIG. 2, it is found that under some conditions, too much water may flowthrough the tertiary siphon 26 and not enough through the secondarysiphon 24. This may result in incomplete expulsion of the air from theupper bend 40 during a flush, and such air interferes with eflicientoperation of the secondary siphon. The step 146 increases the proportionof flow from the primary siphon conducted by the secondary siphon.

The cross-section of tertiary siphon 26 is made relatively larger thanthat of the FIGS. 1 and 2 embodiment. Typically, the area A1 of thetertiary siphon 26 is nearly one-third the area A2 of secondary siphon24. With this area relation, it is found that the tertiary siphon 26draws more efficiently, and secondary air inlet 66' can be lowered, sothat more rapid draining of secondary reservoir 70' can be allowed.

It will further be noted that the secondary siphon contains a venturi atits outlet, the venturi being formed by rounded projections 148, 149.The venturi is provided because it is found that air sometimes tends towork its way up the secondary siphon outlet during siphoning and destroythe secondary siphon action. This does not occur during a flush over atoilet bowl where the secondary siphon outlet discharges into arestricted channel, but it may occur if the device is discharging intoan unrestricted space. The venturi increases the water velocity justabove the secondary siphon outlet and makes it more difficult for air toenter this outlet. A similar venturi may if desired be provided at theoutlet of the tertiary siphon, as indicated in dotted lines at 150, 151.

The next feature of the FIGS. 13 to 15 embodiment is that the secondaryair inlet 66' is formed by a flared mouth 152 on conduit 68. The reasonfor this is that when the water level in the secondary reservoir 70drops below the secondary air inlet 66, it is important that a cleanbreak be made in the siphoning action of the primary siphon. When themouth of conduit 68 is not flared, surface tension sometimes causeswater to cling to the mouth of the conduit, so that it sometimes sucksan air and water mixture, resulting in an ill-defined break of theprimary siphon. This can result in disturbance of the tertiary siphon sothat it will not suck enough water from the intermediate bend 42. With aflared mouth 152, there is less tendency for the secondary air inlet tosuck water when it becomes exposed to the air. This is because thelarger mouth 152 reduces the velocity past the mouth.

In addition, steps indicated in dotted lines at 160 may be formed inconduit 68'. The steps 160 reduce the amount of water sucked throughthis conduit.

It will also be noted that the V-shape of the secondary reservoir 70" ismore pronounced than that of secondary reservoir 70 of FIGS. 1 and 2.This increases the capacity of reservoir 70 (so that aperture 74 may belarge) and ensures that as the secondary reservoir drains, the waterlevel in it will accelerate more rapidly downwardly to produce a cleanerbreak of the primary siphon.

In order to adjust the size of the aperture 74', a shield 154 isprovided, rotatably mounted on the cover plate 72' above aperture 74'.As shield 154 is rotated, it will close aperture 74 to an adjustabledegree, so that the rate at which the secondary reservoir 70 drains (andtherefore the water level in tank 72' at which flushing terminates) canbe adjusted as desired.

It will further be noted that the primary siphon crosssection tapers ordiminishes from the inlet 30' to the midpoint 156 of the primary siphonupper bend 34'. (The width of the device into the paper is substantiallyuniform, except for the outlet end 54'.) This tapering allows extra airto be compressed in the primary siphon outlet leg 32' and in upper bend34' during tank refilling, in order to help drive any excess water fromthe outlet leg of the primary siphon.

It will be appreciated that various further changes can be made in theinvention as described. For example, the dam heights of the primary andtertiary siphons have been shown as the same, but these could be madedilferent. Further, the tertiary siphon 26 has been shown as formedwithin the secondary siphon 24, but it could be formed as a separatetube, which in the case of a toilet (and in fact in most cases) wouldlead to the same location as the outlet of the secondary siphon.However, the relative heights of the tertiary and secondary siphonsshould be maintained, since the tertiary siphon should siphon before thesecondary siphon begins to overflow (otherwise the tertiary siphon maynot become primed), and since the secondary siphon should begin tooverflow after the tertiary siphon is primed.

Although two siphons in series have been shown (i.e. the primary andsecondary siphons), the principles of the invention can be extended tothree siphons in series, with appropriate modifications.

Although the invention has been described in terms of a siphon flushingdevice for a toilet, the invention may be employed in other appropriateapplications where liquid valving is required.

Reference is next made to FIGS. 16 and 17, which show diagrammatically amodification of the invention. In these figures, double primed referencenumerals indicate parts corresponding to those of FIGS. 1 to 12.

In the FIGS. 16 and 17 embodiment, the secondary reservoir 70 of FIGS. 1to 12 has been eliminated. The time delay needed during a flush, so thatsecondary air inlet 66" will not be allowed to break the primary sip-honprematurely, is provided by a time delay mechanism in the push button64".

The push button 64", shown diagrammatically in section in FIG. 16, has afront portion 200 basically the same as the push button 64 of FIG. 6, sothat front portion 200 need not be described further. The push button 64also has a rear portion 202, which includes an extension 204 to push rod118" extending into a depression 206 in a shaft 208. Shaft 208 isoperatively coupled to a conventional delay timing mechanism 210 (whichmay be a mechanical timer, plastic timing strip, etc.) so that whenshaft 208 is pushed in (which occurs upon initiation of a flush), itdoes not return to the position shown in FIG. 16 until about ten secondshave elapsed. Shaft 208 includes a duct 211 therein communicatingbetween a fork 212 in the conduit 62" and a second conduit 214. Theconduit 214 (see FIG. 17) leads into the tank 12 and has an opening inits lower end to define the secondary air inlet 66".

In addition, the fitting 60" includes a duct 68" extending therefrom tojust above the inlet 30" to define another air inlet 216.

During a flush, as the water is emptying rapidly from the tank 12", thesecondary air inlet 66" is blocked from communicating atmospheric air tothe primary siphon by reason of shaft 208, which blocks air passagebetween conduits 212, 214. The flushing action stops by reason ofconduit 68" and opening 216, which breaks the primary siphon. After theflush or at the latter stages of the flush, the shaft 208 returns to itsillustrated position and secondary air inlet 66" communicates air to theprimary siphon again. Refilling then proceeds essentially as previouslydescribed.

During a correcting action, the push button 64 is not pushed. Therefore,the secondary air inlet 66" communicates air to the primary siphon afterthe tank water level has dropped to about the half way mark. Thetertiary siphon then removes the water from the intermediate bend 42"except that needed to form a Water trap, and the tank 12" refills aspreviously described.

What I claim as my invention is:

1. In a siphon valve for a primary liquid reservoir, said valve being ofthe type having:

(a) a primary and a secondary siphon each having an inlet leg and anoutlet leg,

(b) and means connecting the outlet leg of the primary siphon to theinlet leg of the secondary siphon for liquid flow therebetween,

the improvement comprising,

(c) means defining a primary air opening in the upper part of saidprimary siphon, said primary air opening being adapted to be coupled toan air release valve to permit escape of air from said primary siphon,

(d) a tertiary siphon having a sectional area smaller than that of saidsecondary siphon and having an inlet located in the inlet leg of saidsecondary siphon and a lower discharge opening,

(e) means defining a secondary air inlet, said secondary air inlet beinglocated at a selected level relative to said primary siphon, and meanscommunicating said secondary air inlet to said primary siphon,

(f) and delay means for admitting atmospheric air through said secondaryair inlet to said primary siphon at a time normally lagging behind thetime when the liquid in said primary reservoir falls to the level ofsaid secondary air inlet.

2. A siphon valve according to claim 1 wherein said delay meanscomprises a secondary liquid reservoir having a timing drain opening toeffect draining of said secondary reservoir at a slow rate then emptyingof said primary liquid reservoir through said primary, secondary andtertiary siphons, said secondary air inlet being located in saidsecondaly reservoir.

3. A siphon valve according to claim 2 wherein said tertiary siphon islocated in said secondary siphon and extends across and along the innerwall of said secondary siphon, the inlet of said tertiary siphon beinglocated substantially above the bottom of said inlet leg of saidsecondary siphon to leave a water trap blocking free air passage betweensaid primary and said secondary siphons.

4. A siphon valve according to claim 3 wherein said primary andsecondary siphons are formed generally in the form of the letter M, theinlet and outlet legs of said primary siphon being spaced apart with acurved upper bend joining them, the inlet and outlet legs of saidsecondary siphon being spaced apart with a curved upper bend joiningthem, the outlet leg of said primary siphon being joined to the inletleg of said secondary siphon by a curved intermediate bend, said devicebeing cast in two vertical halves, said halves being bonded together.

5. A siphon valve according to claim 2 wherein said primary andsecondary siphons are formed generally in the shape of the letter M,with the outlet leg of said primary siphon being spaced from the inletleg of said secondary siphon and being joined thereto by an intermediatebend, said secondary reservoir being located between the outlet leg ofsaid primary siphon and the inlet leg of said secondary siphon andincluding a pair of side members closing the sides of the space betweenthe outlet leg of the primary siphon and the inlet leg of the secondarysiphon, said drain aperture being located in one of said side members.

6. A siphon valve according to claim 5 wherein said secondary air inletis located at a height about half way up the height of the outlet leg ofsaid primary siphon, said means communicating said secondary air inletto said primary siphon being a duct extending into said primary airopening.

7. A siphon valve according to claim 2 wherein said secondary reservoiris V-shaped, tapering in width below its top, so that as water drainsfrom said secondary reservoir, the water level in said secondaryreservoir will accelerate downwardly.

8. A siphon valve according to claim 5 wherein said secondary reservoiris V-shaped, tapering in width below its top, so that as water drainsfrom said secondary reservoir, the water level in said secondaryreservoir will accelerate downwardly.

9. A siphon valve according to claim 2 wherein said means defining saidsecondary air inlet and said means communicating said secondary airinlet to said primary siphon comprise a duct extending into said primaryair opening, said duct having an enlarged opening at its end definingsaid secondary air inlet.

10. A siphon valve according to claim 2 wherein the inlet and outletlegs of said primary siphon are joined by an upper bend, the interiorcross-section of said primary siphon decreasing from its inlet to aposition halfway around said upper bend.

11. In a siphon valve, for a toilet reservoir or like liquid reservoirof the type provided with an inlet valve for normally delivering liquidinto said reservoir at a predetermined rate, said siphon valve being ofthe type having primary and secondary siphons, each having an inlet andan outlet leg and an upper bend joining said inlet and outlet legs, andan intermediate bend joining the outlet leg of said primary siphon tothe inlet leg of said secondary siphon, the outlet leg of said secondarysiphon extending substantially below the inlet leg of said primarysiphon extending substantially below the inlet leg of said primarysiphon to provide a net head of pressure for said siphon valve, theimprovement comprising:

(a) means defining a primary air opening in the upper bend of saidprimary siphon, said primary air opening being adapted to be connectedto an air release valve to permit escape of air from said primarysiphon,

(b) means defining a secondary air inlet located below said primary airopening and communicating with said primary siphon, to admit atmosphericair to said primary siphon when liquid in said reservoir falls below apredetermined level thus to terminate valving action,

(c) a tertiary siphon within said secondary siphon, said tertiary siphonhaving an inlet opening within said said secondary siphon slightly abovethe top of said intermediate bend,

(d) the cross-sectional area of said tertiary siphon being less thanthat of said secondary siphon but being sufiicient for said tertiarysiphon to conduct liquid at a flow rate greater than said predeterminedrate.

12. A siphon valve according to claim 11 wherein the cross-sectionalarea of said tertiary siphon is about onequarter that of said secondarysiphon.

13. A siphon valve according to claim 11 wherein said primary airopening is located in the upper wall of said upper bend of said primarysiphon, at a position about 45 degrees downstream from the uppermostpoint of said upper wall.

14. A siphon valve according to claim 11 wherein the upper bends of saidprimary and secondary siphons are at the same effective height abovesaid intermediate bend, and the bottom of said primary siphon is locatedat a height between the upper and lower limits of said inter mediatebend.

15. A siphon valve according to claim 11 wherein said secondary airinlet is located at a height intermediate the height of said primarysiphon, said valve further including delay means for communicating airthrough said secondary inlet to said primary siphon at a time normallylagging behind the time when liquid in said reservoir falls to the levelof said secondary air inlet.

16. A siphon valve according to claim 15 wherein said delay meanscomprises a secondary liquid reservoir having a timing drain opening toeffect draining of said secondary reservoir at a slower rate thenemptying of said first mentioned liquid reservoir through said primary,sec ondary, and tertiary siphons, said secondary air inlet being locatedin said secondary reservoir, said means communicating said secondary airinlet to said primary siphon being a conduit communicating saidsecondary air inlet to said primary air opening.

17. A siphon valve according to claim 11 including means defining aventuri within said secondary siphon 15 adjacent the outlet of saidsecondary siphon, to reduce the likelihood of air entering the outlet ofsaid secondary siphon during liquid flow therethrough.

18. A siphon valve according to claim 11 wherein the inlet of saidtertiary siphon is stepped inwardly in the inner wall of said secondarysiphon thereby to increase the proportion of liquid from said primarysiphon entering said secondary siphon and to reduce the proportion ofliquid from said primary siphon entering said tertiary siphon.

19. A siphon valve according to claim 11 wherein said secondary siphonincludes a bowl refill aperture adapted to be connected to a bowl refillconduit from said inlet valve, said bowl refill aperture being locatedfor liquid passing therethrough to discharge into said outlet leg ofsaid secondary siphon, so that after a flush, water entering said bowlrefill aperture falls through said outlet leg of said secondary siphonto refill a toilet bowl located therebelow.

20. A siphon valve according to claim 19 including a bowl refill tubeextending from said bowl refill aperture in a direction such that liquidflowing through said bowl refill tube and entering said secondary siphonwill, at its point of entry into said secondary siphon, flow insubstantially the same direction as liquid flowing through said siphon,thereby to assist the flow of liquid through said secondary siphon.

21. A siphon valve according to claim 19 wherein said bowl refill tubeextends upwardly above the normal liquid level maintained in said firstmentioned reservoir by said inlet valve, said bowl refill tube being ofa first diameter and including as its upper surface a tubular projectionof diameter substantially less than said first diameter, said tubularprojection being adapted to be connected to said bowl refill conduitfrom said inlet valve.

22. A siphon valve according to claim 11 wherein said tertiary siphonextends laterally across the lower part of said upper bend of siadsecondary siphon, and said tertiary and secondary siphons arerectangular in cross-section in the region of said upper bend of saidsecondary siphon.

23. A siphon valve according to claim 1 wherein said secondary siphonincludes a bowl refill aperture therein in its upper surface above theoutlet leg thereof, said siphon valve further including an anti-siphonbowl refill tube extending upwardly from said refill aperture, saidrefill tube being of a first diameter to a height above the normalheight of liquid in said reservoir, and said refill tube being adaptedat its top to receive a smaller diameter bowl refill conduit extendingto an inlet valve of said reservoir.

24. A siphon valve according to claim 23 including a liquid levelindicator plate mounted on said refill tube to indicate the normallydesirable height of liquid in said reservoir.

25. In a siphon valve, for a toilet tank of the type having an inletvalve and a float connected to said inlet valve to admit water to saidtank to a predetermined level, said siphon valve being of the typeincluding at least two 16 siphons connected in series to control andconduct water from said tank into a toilet bowl located therebelow, oneof said siphons having an outlet leg adapted to discharge into saidtoilet bowl, the improvement comprising an anti siphon bowl refill tubeincluding:

(a) a tube of a first diameter connected to said outlet leg to dischargeinto said outlet leg, said tube extending upwardly above saidpredetermined level,

(b) said tube including a tubular projection above said predeterminedlevel for connection to said inlet valve, said tubular projection beingsubstantially smaller in diameter than said tube.

26. Apparatus according to claim 25 including a water level indicatorplate mounted on said tube to indicate an optimum water level in saidtank.

27. Apparatus according to claim 26 wherein said tube is oriented todischarge into said outlet leg in a direction such that waterpassingthrough said tube into said outlet leg assists flow of waterthrough said outlet leg.

28. In a siphon valve, for a primary liquid reservoir of the typeadapted normally to contain liquid to a predetermined level, said valvebeing of the type including primary and secondary siphons connected inseries to control and conduct water flow from said primary reservoir,the improvement comprising:

(a) a secondary liquid reservoir adapted to be located to fill when theliquid in said primary reservoir reaches said predetermined level,

(b) said secondary reservoir having a drain aperture therein to permitliquid to drain from said secondary reservoir at a rate slower than therate of fall of the liquid level in said primary reservoir duringdraining of said primary reservoir by said valve,

(c) means in said secondary reservoir defining an air inlet at aselected level in said secondary reservoir,

(d) and means communicating said air inlet to said primary siphon.

29. A siphon valve according to claim 28 wherein said secondaryreservoir diminishes in cross-section from its top to its bottom.

References Cited UNITED STATES PATENTS 853,705 5/1907 Lindenberg et al.137-128 1,077,471 11/1913 Herzfield 137128 1,421,531 7/1922 Morasl37l2'8 2,606,326 8/1952 Niccolai 4-43 FOREIGN PATENTS 607,101 12/ 1934Germany.

581,222 8/ 1958 Italy.

LAVERNE D. GEIGER, Primary Examiner H. K. ARTIS, Assistant Examiner U.S.Cl. X.R. 137-124, 142

